The gymnasium that has stood for 36 years at Blacksburg High School began coming apart as the girls basketball team progressed through a late Saturday morning practice this past weekend.

First came a groan, then a shudder.

Chunks of a wall from high above the scoreboard fell to the floor, barely missing several players.

The youngsters looked up to see a gaping fracture in the wall.

"Our coach was like, 'OK, practice is over,' " player Katy Kipps recalled.

That call was a life-saver. With all staff, students and visitors out, the gymnasium roof collapsed about two hours later shortly before 1:37 p.m., putting the 1,200-student high school out of operation at least into early this week.

Students and school officials were chalking it up to sheer luck -- or even God's protection -- that no one was inside the heavily used sports center when the roof caved in. No one was injured in the incident.

Had the collapse occurred during Friday night's boys basketball contest or during one of the practices or games scheduled in the days following, dozens or even hundreds of people would have been inside.

Wendell Jones, chairman of the board of Montgomery County Public Schools, said he doubts such a collapse would have been survivable.

"Thank God it didn't happen," Jones said.

Now the gym is rubble.

The last players to use the 36-year-old arena vividly recall the warning signs that the structure gave before its demise.

The team of 12 had just paused for a strategy discussion with their coach when they first realized something was wrong.

"We all of a sudden heard this really odd rumbling noise, kind of like an earthquake," said Kipps, who plays center.

"Then I saw the basketball goal drop a whole foot practically."

A beam holding up a basket had shifted, she recalled.

"And then I turned around; I heard this crackling noise and I saw in the corner there was a huge gap and whole bunch of cement blocks coming down.

"I moved out of the way," she said.

Not far away was point guard Lindsey Henderson.

"We were like, 'Why did that just fall?' " Henderson said.

Her dad, Roger Henderson, called an end to practice.

But before they left the arena for the last time, the quick-thinking students snapped cellphone pictures of a large crack in the wall and debris on the court.

School officials moved in to assess the situation.

"They quickly determined they needed to vacate the building based on what they saw from the structure damage," Jones said.

A check was made to ensure no one was inside the school, Jones said. Officials left and "were out in the parking lot" when the gym collapsed, Jones said.

Lacey McMahan, who plays point guard, said she was not especially scared by the incident that cut short practice.

But once she combined what she witnessed with the fact that the building collapsed a short time later, "that's the scary part," she said.

And, there is sadness.

McMahan has racked up a high school career scoring total of 985 points. She intended to break the 1,000-point mark during a home game that had been scheduled for today.

Sinking the 1,000th point at Blacksburg High would have been sweet.

"Now it doesn't look that it's going to happen," she said.

Her next game will be at Blacksburg Middle School tonight, in the first round of the River Ridge District tournament.